In access link and node redundancy for service provider based Layer 2 Virtual Private Network (L2VPN) services, customers typically desire resilient site multi-homing access capabilities that are similar to Layer 3 VPN services. However, redundancy in the L2VPN topologies is much more complex compared to Layer 3 VPN topologies because of potential Ethernet frame looping conditions.
One solution to avoid looping conditions is to apply a spanning tree protocol. However, the spanning tree protocol has problems with scalability, and can also result in looping conditions if the spanning tree protocol is misconfigured. Additionally, the spanning tree protocol is typically run “over the top” of a service provider's network and thus the service provider has no control or visibility that the solution is enabled and working properly.